Imagine you place a knight chess piece on a phone dial. 
Suppose you dial keys on the keypad using only hops a knight can make . 
How many  distinct members can you dial in N hops from a particular start. 

1 2 3
4 5 6
7 8 9 
* 0 #

input: 
startingPosition = 6, 
hops = 2

output: 6